The invention comprises an improvement in the reciprocating machine disclosed in U.S. Pat. No. 5,762,480, issued to Carmeli Adahan.
A reciprocating piston engine capable of embodying the improvements of the present invention, like the reciprocating machine of the '480 patent, converts linear reciprocating motion of the piston in the cylinder to rotary motion of a power output shaft wherein the piston is drivably connected to the power output shaft through a connecting rod that moves in a substantially linear fashion. Side loading of the piston is avoided since there are minimal transverse force components associated with the force exerted on the piston by the piston rod. The absence of transverse loading on the piston avoids piston and cylinder wear due to frictional contact between the piston and the surrounding wall of the cylinder.
The reciprocating machine of the '480 patent is characterized also by a reduction in the speed of travel of the piston as the piston reaches its top dead center position. This increases the mechanical efficiency of the reciprocating engine.
In the case of a conventional engine with a crankshaft and a connecting rod between the piston and the crankshaft, it is possible to adjust the compression ratio by changing the effective length of the connecting rod. An example of a hydraulic piston and cylinder mechanism for adjusting the piston rod length is described, for example, in SAE Technical Paper No. 920453, by Kajiwara. The effective connecting rod length can be changed also by a cam and eccentric mechanism, as described in U.S. Pat. No. 4,319,498.
A double connecting rod assembly for a reciprocating piston engine is disclosed in U.S. Pat. No. 4,437,438, which includes a swinging lever that is connected to both elements of a two-piece connecting rod assembly, resulting in higher friction compared to the engine of the '498 patent.
A guide rod in a double connecting rod assembly is disclosed in prior art U.S. Pat. No. 4,131,094, wherein the pivot axis for the guide rod can be changed to alter the effective compression ratio of the reciprocating piston engine.
None of the teachings of these prior art devices is adaptable for use with an engine of the Adahan type to vary compression ratio. Each of the prior art devices for achieving a variable compression ratio increases the effective overall length, weight and friction of the piston and cylinder assembly.